1. Field of the Invention
The present invention relates to a disposable cartridge for characterizing particles suspended in a liquid, especially a self-contained disposable cartridge for single-use analysis, such as for single-use analysis of a small quantity of whole blood. The self-contained disposable cartridge facilitates a straightforward testing procedure, which can be performed by most people without any particular education. Furthermore, the apparatus used to perform the test on the cartridge, could be made simple, light and maintenance free, thus giving full portability and a large range of operation for the user. The invention provides steps for pre-analytic handling of samples such as hemolysing of red blood cells and inactivation of coagulation.
2.Description of the Background Art
Present instruments for particle characterization such as counting and sizing are fairly expensive, immobile and require operation by trained personnel. The consequence hereof has been that many instruments are placed in dedicated laboratories that are operated by specialized personnel. Furthermore, the samples to be analysed must be transported to this laboratory and the results are reported back to the requiree.
In WO 01/11338, which is hereby incorporated by reference, an apparatus is disclosed for characterizing particles suspended in a liquid, comprising a disposable cartridge and a docking station for removably receiving the cartridge. The cartridge comprises a housing with a first collection chamber bounded by a wall containing an orifice for the passage of the particles and having an inlet/outlet for connection to a source of positive or negative gas pressure, and components of a particle characterization device for characterizing particles passing through the orifice that are connectable from outside the housing. The docking station comprises a port for connection with a source of positive or negative gas pressure and forming a gas connection with the inlet/outlet when the cartridge is received in the docking station, and means for operative connection with the components of a particle characterization device when the cartridge is received in the docking station.
In WO 02/089670, which is hereby incorporated by reference, a device for sampling a small and precise volume of liquid is disclosed, comprising a movable member with a cavity for entrapment and displacement of an accurate part of a liquid sample.
It is a disadvantage of these prior art devices that several devices are used to perform an analysis, e.g. of a whole blood sample. The sample taking is performed with a separate device, and the sample has to be transferred to another device for sample preparation before it is finally transferred to a sensor for analysis.
In WO 99/01742 a disposable sampling device is disclosed for an apparatus for counting particles contained in a liquid. The sampling device is connectable in a defined position to the apparatus. The device has means for introducing a sample therein, means for metering a defined volume of the sample, means containing a defined volume of a diluting liquid, a diluting chamber, means for simultaneously directing the defined volume of sample and the defined volume of diluting liquid to the diluting chamber for obtaining therein a diluted sample, means for directing at least a portion of the diluted sample past particle counting means and signal transmitting means connecting the particle counting means and terminal means located at an outer boundary of the housing in a position corresponding to a location of terminal means of the apparatus when the housing is connected thereto in the defined position.
During blood analysis with the device described in WO 99/01742, the blood sample is pumped back and forth several times for dilution, mixing and analysis, and the flow system is closed so that the pressure in the system is increased and decreased above and below, respectively, atmospheric pressure during movement of the sample. Further, sample taking requires pumping with a membrane or another flow actuator causing entrance of blood into the flow system of the device. Thus, the above disclosed flow system is rather complicated.
The particle counting is, as described in WO 99/01742, performed in an open-ended tube so that the volume of diluted sample passing the particle counting sensor is very small.
The blood analysis, as described in WO 99/01742 does not take into account that particles of different kind and concentration might need pre-analytic separation, decomposition, staining or labeling in order to be accurately recorded by the sensing principle in account.
The blood test sequence as described in WO 99/01742 does not take into account that users without prior education herein should be able to learn how to perform this test themselves, i.e. no pre-analytical dilution steps should be required.